Method of operation for a magnetic resonance imaging suite

ABSTRACT

A method of operation for a magnetic resonance imaging suite. A power supply of magnetic resonance injector system receives electrical power from an AC power outlet, both of which are located outside of a shielded room of the magnetic resonance imaging suite. Electrical power from the power supply of the magnetic resonance injector system is conveyed (via an appropriate power connection) into the shielded room of the magnetic resonance imaging suite and to a component (e.g., a power head) of the magnetic resonance injector system located inside the shielded room. While this electrical power is being conveyed, radio frequency energy emitted from the power connection is being filtered.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of co-pending U.S. patent applicationSer. No. 09/851,462 filed on 8 May 2001 and entitled “Remotely PoweredMR Injector”, the disclosure of which is hereby incorporated byreference.

FIELD OF THE INVENTION

The invention relates to contrast media power injectors compatible foruse within a magnetic resonance imaging (MRI) suite, and in particular,to electrical interconnection of components of a magnetic resonance (MR)injector.

BACKGROUND

A Magnetic Resonance Imaging (MRI) unit consists of a large cylindricalsuperconducting magnet for generating a strong magnetic field, devicesfor transmitting and receiving radio waves, and a complex computersystem. When a patient lies inside the MRI unit, the strong magneticfield causes the hydrogen nuclei in the patient to line up. Alow-frequency radio wave is pulsed through the magnet into the patient.The hydrogen atoms absorb the energy released by the radio waves. Thisdisrupts the uniformity of the nuclei. When the radio-wave stimulationstops, the nuclei return to their original state and emit energy in theform of weak radio frequency (RF) signals. The strength and length ofthese RF signals—and therefore the kind of image produced—depend on theproperties of the organ or tissue involved. A computer translates the RFsignals into highly detailed cross-sectional images. The images areessentially maps of the locations of water or hydrogen in the body. Themagnetic field produced by the MRI unit constrains installation ofassociated MRI equipment. In particular, any ferromagnetic object nearthe MRI unit will be attracted by the magnetic field, either impairingoperation of the equipment or becoming a safety hazard if forciblyprojected toward the MRI unit. Also, the uniformity of the magneticfield of the MRI unit is altered by ferromagnetic material, even if theferromagnetic material is secured to prevent safety hazards.Consequently, ferromagnetic material is generally kept away from the MRIunit.

The radio frequency transmissions emitted by the MRI unit toward thepatient also poses electromagnetic interference/compatibility (EMIC)constraints on the installation of other equipment. General consumer andmedical equipment such as personal computers and monitors are typicallyinadequately shielded to prevent impairment of function due to thestrength of such RF emissions. Inversely, the MRI unit is susceptible todegraded performance if RF noise from other equipment distorts thereceived RF signal during imaging.

For these reasons, the core of the MRI unit, including the magneticfield producing and RF transmission and receiving portions, is placedwithin a magnet room that is shielded from the other rooms of the MRIsuite and the rest of the facility. Often, nonferrous metal sheets ormesh encompass the entire magnet room to prevent magnetic energy and RFenergy from entering or leaving the magnet room. Consequently, the MRIunit generally includes highly shielded electrical power, data andcontrol cabling that are routed through filtered and grounded accesspoints so that susceptible or interfering components of the MRI unit maybe placed outside of the shielded room.

The same installation constraints affect installation of other equipmentin the shielded magnet room. For example, utility electrical power,typically provided as AC outlets throughout the facility, is atransmission path for RF noise and is thus often not provided in theshielded magnet room. Similarly, sensors and controls for equipment usedin the MRI suite often have to be placed in another room of the MRIsuite, typically either an equipment room or control room. Thesecontrols are connected to the magnet room via a penetration panel thatmaintains the EMI shielding while allowing penetration by shielded andfiltered electrical cables.

As MRI units became capable of increased computational speed,opportunities were presented for use of contrast media, injected intopatients before or during an MRI scan, to enhance dynamic imagingstudies. In addition, contrast media were developed that allowed MRIscanning of certain types of tissues that otherwise were insufficientlydistinguishable from surrounding tissue for effective MRI diagnosticstudies. Power injectors for contrast media are sometimes preferred dueto repeatability of dosage volumes and injection rates and keepingpersonnel away from the MRI unit during a scan. However, adaptingcontrast media injectors from other radiological modalities (e.g.,X-ray, Computer-aided Tomography (CT), etc.) was difficult due to MRIunit installation limitations.

With reference to FIG. 1, a power injector system 10 for injectingimage-enhancing contrast media into a patient before or during an MRIscan is depicted as installed in an MRI suite 12. In particular, thepower injector system 10 depicted is an OPTISTAR™ magnetic resonance(MR) digital injection system available from Mallinckrodt,Liebel-Flarsheim Business, Cincinnati, Ohio. The system 10 successfullyoperates within an MRI suite 12 by placement of components at varyingdistances from an MRI unit 14 or with varying degrees of shielding. Inparticular, a power head 16 contains ultrasonic motors. The ultrasonicmotors operate syringes to dispense contrast media and saline solutioninto a patient as commanded and powered over a shielded power head cable18 by a power control 20.

The power control 20 is also within a shielded magnet room 22 of the MRIsuite 12 along with the power head 16 and the MRI unit 14, althoughgenerally spaced away from the MRI unit 14 to reduce the EMICconsiderations. Since AC outlets are generally not available in theshielded magnet room 22, the power control 20 is battery powered. Thepower control 20 provides power to the power head 16 in response to datasignals that are relayed from the power head 16 to the power control 20and between the power control 20 and a touch-screen console 24 outsideof the shielded magnet room 22. In particular, a shielded electricalcable 26 for transferring data signals couples the power control 20 toan opening, such as a free hanging D-shell connector 28, in apenetration panel 30. An electrical cable 32 outside of the shieldedmagnet room 22 is electrically coupled to the other electrical cable 26inside the shielded magnet room 22 via a filter 34 connected to thepenetration panel 30. The filter 34 reduces RF noise induced on thecables 26, 32. In the depicted MRI suite 12, the cable 32 passes from anequipment room 36 that is positioned adjacent to the penetration panel30 to a control room 38 where the MRI unit controls (not shown) and thepower injector touch-screen console 24 reside.

Since the power control 20, and thus the power head 16, is batterypowered, a battery charger 40 is placed in the control room 38 forrecharging a battery 42 for use in the power control 20. The batterycharger 40 receives its power from an AC outlet 44. Thus, aninconvenient task is placed on operators of the MRI unit 14 andbattery-powered injector system 10 to monitor the state of charge ofbatteries 42 and swap batteries between the battery charger 40 and thepower control 20. If an undercharge of batteries 42 installed in thepower control 20 is not detected in a timely fashion, the operation ofthe MRI unit 14 is delayed, reducing the number of patients that may bescanned. Such reduction in the number of patients increases medicalcosts and limits delivery of medical services.

In addition to clinical and staffing considerations, there is theincreased inventory of batteries 42 necessary to have sufficientbatteries for both use and simultaneous recharging. Furthermore, use ofbattery power places design constraints upon the battery-poweredinjector system 10, such as reducing functionality or increasing thesize and cost of the batteries 42 to handle the power demand.

As an example of a design constraint, the power control 20 providespower for the electronic components and the ultrasonic motors of thepower head 16 and the electronic components of the power control 20itself. The power control 20 does not power components outside themagnet room 22. Consequently, several of the major components of thebattery-powered injector system 10 each individually have internal powersupplies that regulate and convert electrical power for use by thatmajor component. For example, the console includes a power supply thatalso receives power from the AC outlet 44 and converts the AC electricalpower to DC voltages useful for the electronics and display devicestherein. Similarly, the battery charger 40 includes an internal powersupply that regulates and converts AC power to voltages suitable for itselectronics and for the battery 42 being recharged. Also, the powercontrol 20 includes an internal power supply for regulating andconverting the battery power from installed batteries 42 for thevoltages required for its operation. Each internal power supplyincreases the cost, the size, and the cooling requirement of each majorcomponent.

Therefore, a significant need exists for an MR injector system withreduced cost that is simpler to operate than current battery-poweredinjector systems.

SUMMARY

The present invention addresses these problems with a remotely poweredMR injector that efficiently utilizes AC electrical power provided atconvenient AC outlets in a control room of an MRI suite. In particular,a remotely positioned power supply supplies the electrical powerrequirements for the entire MR injector system. Operators are no longerinconvenienced by charging and replacing batteries. In addition,installation of the MR injector system is enhanced by incorporatingelectrical power transmission into shielded electrical cables that alsotransmit data signals.

In one particular aspect of the present invention, a power supplyoutside of the shielded magnet room provides electrical power to a powerhead inside of the shielded magnet room via electrical cables coupledthrough a penetration panel.

In another aspect of the present invention, the power supply replaces abattery charger in an existing battery-powered injector system byproviding electrical power across the penetration panel to a powercontrol inside the shielded magnet room. The power control actuates apower head, which is near an MRI unit, to inject contrast agent andsaline into patients undergoing an MRI scan. In particular, electricalpower from an electrical cable from the penetration panel isinterconnected with internal conductors of the power control thatpreviously received power from a battery. The power supply is thusconfigured to provide electrical power equivalent to those ofpreviously-used batteries. Thereby, existing MR injector systems receivemany of the benefits provided by a remotely powered MR injector system.

The above and other objects and advantages of the present inventionshall be made apparent from the accompanying figures and the descriptionthereof.

BRIEF DESCRIPTION OF THE FIGURES

The accompanying figures, which are incorporated in and constitute apart of this specification, illustrate embodiments of the invention and,together with a general description of the invention given above, andthe detailed description of the embodiments given below, serve toexplain the principles of the invention.

FIG. 1 is schematic of a prior art battery-powered injector installed ina magnetic resonance imaging (MRI) suite; and

FIG. 2 is a schematic of a power injector consistent with the presentinvention with components installed in the magnet room directly poweredby other components installed outside of the magnet room.

DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS

Turning to FIG. 2, a remotely powered MR injector system 50 consistentwith the present invention is installed in an MRI suite 52 having amagnet room 54 enclosed within EMI shielded walls 56. Other portions ofthe MRI suite 52, depicted as an equipment room 58 and a control room60, are electrically accessible to the magnet room 54 via a penetrationpanel 62 in the EMI shielded walls 56. A power supply 64 of the system50 advantageously provides electrical power to the entire system 50,reaching portions of the system 50 within the magnet room 54 via thepenetration panel 62, thereby eliminating the need for battery power topower a power head 66 near an MRI unit 68.

The power supply 64 simplifies installation in the MRI suite 52 byaccessing a standard AC outlet 70 in the control room 60. In theillustrative embodiment, the power supply 64 converts standard utilityAC power from the outlet 70 into several forms suitable for the othermajor components of the system 50 with an AC-DC switcher 72, such as aGPM225 global performance switcher available from Condor D.C. PowerSupplies, Inc. of Oxnard, Calif. This AC-DC switcher 72 is suitable foruse in a medical facility such as control room 60 and may be flexiblysupplied from outlet power ranging from 28-264 Vac, 47-63 Hz singlephase. Examples of alternative implementations of switcher 72 includethe PM200 Series of AC-DC switching power supplies from InternationalPower Sources, Inc. of Holliston, Mass.

For an existing OPTISTAR™ MR system, the power supply 64 advantageouslyemulates the power performance of the batteries installed into aconventional power control 74 in the magnet room 22. Specifically, afirst electrical cable 76 outside of the magnet room 22 couples thepower supply 64 to the penetration panel 62. The first electrical cableincludes data conductors 78 suitable for electronic data signals forsensing and command signals and power conductors 80 suitable forelectrical power signals for powering electronics and electro-mechanicaldevices (e.g., ultrasonic motors of power head 66). For instance, thepower conductors 80 may be coupled to the battery compartment 81 toutilize existing electrical power wiring in the power control 74.

The first cable 76 connects to a conventional RF filter 86 at thepenetration panel 62. The RF filter 86 grounds conductive shields of thefirst cable 76 so that induced noise on the shields is reduced at theEMI shielded wall 56. Also, the RF filter 86 attenuates RF noise on dataand power conductors 76, 80 within a rejection frequency band selectedto correspond to the RF frequencies used by the MRI unit 68. On theinside of the magnet room 54, the other side of the penetration panelelectrically couples to a second electrical cable 84 via a free hangingD-shell connector (not shown). The other end of the second cable 84couples to the power control 74. Like the first cable 76, the secondelectrical cable 84 includes data conductors 88 suitable for electronicdata signals for sensing and command signals and power conductors 90suitable for electrical power signals for powering electronics andelectro-mechanical devices.

It will be appreciated that additional interconnections may be made,such as wall connector (not shown) in the wall 91 between the consoleroom 60 and the equipment room 58. Similarly, instead of one cable 76,84, 98, respectively, between major components 64, 66, 74, 94 of thesystem 50, a plurality of cables electrically run in parallel may beused.

The power control 74 includes power head control electronics 92 thatreceives feedback and any operator commands input at the power head 66.The power head control electronics 92 further provides operation statusdata to a touch-screen console 94 in the control room 60 for display toan operator. The power head control electronics 92 also receivescommands from the console 94 and responds by activating a DC-AC ultrasonic motor drive 96 to produce a signal over a power head cable 98 tothe power head 66 to actuate syringe plungers to dispense contrast mediaand/or saline solution.

The power supply 64 facilitates communication between the console andpower control 74 by including a data link 100 that couples the firstcable 76 to a console cable 102. The console cable 102 advantageouslyincludes data conductors 104 for conducting data signals and powerconductors 106 for powering the console 94. Alternatively or in additionto power conductors 106, the power supply 64 may include aninterconnection between the AC power received from the AC outlet 70 toan AC outlet 108 externally mounted for a conventional electrical plugof a conventional monitor 94. The data link 100 may further include anoriginal equipment manufacturer (OEM) data port 110 for later upgradesto the system 50.

In use, an operator of a remotely powered MR injector system 50 installsa console 94 and power supply 64 in a control room 60 of an MRI suite 52by plugging the power supply 64 into an AC outlet 70. A console cable102 is connected between the console 94 and the power supply 64. A powercontrol 74 and a power head 66 are positioned within the magnet room 54.Specifically, the power head 66 is placed proximate to the MRI unit 68and connected via power head cable 98 to the power control 74. The powercontrol 74 is spaced away from the MR unit 68. Ideally, anyferromagnetic components of the power control 74 are not only shielded,but also oriented such that the entire power control 74 may be orientedwith respect to the magnetic field from the MRI unit to minimizemagnetic field interruption. Communication between the portions of thesystem in rooms 54, 60 is facilitated by cables 76, 84 between the powersupply 64 and power control 74. In addition, cables 76, 84 include powerconductors 80, 90 to remotely power the power head 66 via power control74.

By virtue of the foregoing, an improved MR injector system 50 isoperable within the demanding EMIC constraints of the MRI suite 52without the inconvenience and additional costs of using battery powerinside the magnet room 54.

While the present invention has been illustrated by a description ofvarious embodiments and while these embodiments have been described inconsiderable detail, it is not the intention of the applicants torestrict or in any way limit the scope of the appended claims to suchdetail. Additional advantages and modifications will readily appear tothose skilled in the art. The invention in its broader aspects istherefore not limited to the specific details, representative apparatusand method, and illustrative example shown and described. Accordingly,departures may be made from such details without departing from thespirit or scope of applicant's general inventive concept.

1. A medical imaging suite comprising: a shielded room having walls thatinclude electromagnetic shielding; an AC power outlet; an MRI unitcomprising a magnet that is located inside the shielded room; and apower injector system comprising: a power head located inside theshielded room, the power head being configured to operate a syringe inorder to dispense contrast media from the syringe; a power supplyaccessing and receiving AC power from the AC power outlet and convertingthe AC power to DC power; and a power connection configured to conveypower from the power supply to the power head, wherein the powerconnection comprises a battery compartment toward which power from thepower supply is conveyed and from which power is conveyed to the powerhead.
 2. The imaging suite of claim 1, wherein the power connectioncomprises a radio frequency filter.
 3. The imaging suite of claim 2,wherein the radio frequency filter grounds conductive shields of thepower connection.
 4. The imaging suite of claim 2, wherein the radiofrequency filter attenuates RF noise within a rejection frequency bandselected to correspond to the RF frequencies used by the MRI unit. 5.The imaging suite of claim 1, wherein the battery compartment is devoidof a battery.
 6. The imaging suite of claim 1, further comprising: acontrol panel located outside the shielded room for generating datasignals in order to control the power head; and a data connectionconfigured to convey data signals from the control panel to the powerhead.
 7. The imaging suite of claim 1, wherein the AC outlet is locatedoutside the shielded room.
 8. The imaging suite of claim 1, wherein thepower supply is located outside the shielded room.
 9. The imaging suiteof claim 1, wherein the power connection comprises a cable configured toconvey power from the power supply toward the battery compartment of theinjector system.
 10. The imaging suite of claim 1, wherein the powerconnection comprises a cable configured to convey power from the batterycompartment of the injector system into the power head of the injectorsystem.
 11. The imaging suite of claim 1, wherein the power headcomprises an ultrasonic motor.
 12. The imaging suite of claim 1 furthercomprising a syringe mounted to the power head of the power injectorsystem.
 13. The imaging suite of claim 12 further comprising contrastmedia disposed within the syringe.